TORCS, The Open Racing Car Simulator is a highly portable multi platform car racing simulation. It is used as ordinary car racing game, as AI racing game and as research platform. It runs on Linux (x86, AMD64 and PPC), FreeBSD, OpenSolaris, MacOSX and Windows.

Smokin' Guns is a GPLv2 licensed first person Western style shooter based on the Quake 3 engine (Id Tech 3) developed by a loosely knit team of developers and artists. This project represents the game engine.

WideStudio is an Integrated Development Environment (IDE) for building window applications in C++, Ruby, Python an Perl for Windows, MacOSX, Linux, FreeBSD, SOLARIS and other unix and BTRON and T-Engine. This is open and free (under MIT/X Consortiun Lice

SPRING is a real-time surgical simulation system with soft-tissue modeling and networked haptics. SPRING is cross-platform (Unix, Windows, and OS X.) Written in C++ with OpenGL, SPRING reads many common 3-D file formats and supports parallel processing.

GeomSpace is interactive geometry software for different geometric spaces. You can build your own universe of any dimension and with any geometry. You can choose Euclidean, elliptic, hyperbolic, Minkowskii among other spaces.

joXSI is a .XSI 3D model file importer for Java. The goal is to have joXSI support everything in the .XSI file format, including inverse kinematics and skinned animation. joXSI is used in Wurm, which is a community-centric fantasy Java MMORPG.

Guanxi is a robust analysis and simulation application for Social Network Analysts. Guanxi allows researchers in the field to create, import, and export an endless array of networks, analyze their structure, and run custom dynamics over them.

A fast, unobtrusive and modern cross-platform GUI toolkit. Agar fully exploits hardware acceleration where available, but also supports simple frame-buffer interfaces. Agar is stand-alone and easily portable to new platforms and graphics systems.

ChemVisio is software which might be useful for educational purposes (non-organic chemistry, crystallography etc.). It might be a good visualization support for all people who need better illustrations than that you could see in books.